Comparison between estimated flows and measures: a study for the hydrographic basin of Branco River/MT

Abstract

Water is an essential resource for life, used for various purposes, so knowing the water conditions of watersheds is important for the management and planning of water resources, providing (as regards) sustainable development. This paper aims to compare the flow data of the Rio Branco watershed, estimated by the grant system with the flow measured in locu in October. The Branco River basin is located between Barra do Bugres and Nova Olímpia, two municipalities in Mato Grosso that stand out for their sugarcane and beef cattle production. Thus, the basin plays an important role for the production systems, regarding the irrigation and desedentation of the animals. River flow measurement was performed by the float method in nine points of the basin, while the estimated flow values ​​were obtained from the Mato Grosso Integrated Environmental Monitoring and Licensing System. Then, the obtained data were statistically analyzed by Spearman's normality and correlation tests. A comparison was also made between the flows at the sampled points. Subsequently, the performance of the estimation method was evaluated using correlation coefficients ‘r’, agreement index ‘d’ and confidence index ‘c’. Finally, the possibility of granting in the basin was analyzed. The results showed lower flow to the springs (P7, P8 and P9), while the other points presented higher water availability, obeying the order of the flow of the tributaries. The comparative analysis showed differences between the estimated flow and the measured flow in locu in all studied points. Spearman's correlation test showed no correlation between flow rates. The performance evaluation of the estimation method revealed low reliability, accuracy and precision, highlighting the fragility of the system. It is also concluded that the Branco river basin needs a grant request in all studied points, enabling better management and planning of the natural resources uses of the basin.